This is mostly off-topic, focusing on Cryptic Crosswords, however there is the occasional run through of The Times "super-fiendish" classic sudoku, and "deadly" killer sudoku.

The Sudoku videos tend to focus on the "Snyder" method of notation, which I personally find a bit annoying - and I think this label is at least a little incomplete given Thomas' excellent talk in Bangalore which elaborated on it a little more - but the videos are nevertheless worth a watch. Simon is a very good Sudoku solver (has participated in WSCs), and Mark is an excellent Sudoku solver (has participated in WSCs and has a Times championship under his belt). There is definitely a lot to be learned watching how to do something by people who are very good at it!

Once in a blue moon Simon also talks through a solve from nikoli.com, although I suspect that has very limited appeal to the channel's audience.